A tilt/telescopic steering device adjusts both vertical positions and front-back positions of a steering wheel in accordance with a driver's body type or a driving posture.
Such position-adjusting steering device is provided with a clamp unit that clamps a specifically positioned column onto a side plate of a mounting bracket by tightening a tightening rod. The clamp unit uses a structure of clamping the column onto the side plate of the mounting bracket through the intermediary of a friction plate (Patent Documents 1 and 2) because the steering device needs to be rigid enough for clamping, provide stable clamping force, and facilitate an unclamp operation.
Such clamp unit uses a layer of friction plates in order to generate large clamping force. A clamp unit described in Patent Document 1 uses a tilt friction plate and a telescopic friction plate in order to increase the clamping rigidity in both the tilt direction and the telescopic direction. The tilt friction plate is extended in the tilt positioning direction and is fixed to the mounting bracket. The telescopic friction plate is extended in the telescopic positioning direction and is fixed to the column. According to a clamp unit described in Patent Document 2, the tilt friction plate is extended in the tilt positioning direction and is fixed to an outer column. The telescopic friction plate is extended in the telescopic positioning direction and is fixed to an inner column.
However, technical skills are required to assemble alternate layers of differently shaped tilt friction plates and telescopic friction plates according to specified directions. The assembly operation is especially difficult when the tilt friction plates and the telescopic friction plates are fixed to different positions.